Jump to content
HybridZ

Using 5/8 bolt in place of spindle pin


Recommended Posts

I have researched replacing the spindle pin with a 5/8 bolt.  I know people have done this before.  I am putting in the Ford super 8.8 kit from InvincibleExtremes (Vlad) and it replaces the spindle pin with a 5/8 bolt.   I also had the (dis)pleasure of removing my factory spindle pins.

 

What I want to know is, when people have used a bolt, what do they tighten the nut torque to?  I have poly bushings, and when the nut is tightened, the metal sleeves of the bushings will tighten against the metal bore of the new upright in the kit. I was worried about the metal to metal contact in this area but this is the same as stock, right?  I was considering putting a thin Delrin washer (thrust washer?)between the bushing sleeves and the upright.  

 

I will be using a nylock nut, and probably another jam nut just to be safe.  But what torque should I tighten the nut to?  I believe factory torque spec is 65 ft-lbs.

 

Thanks

Edited by fusion
Link to post
Share on other sites
  • Replies 46
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

Since the 5/8" all thread is smaller than the original pin over time you will develop what is called fretting. The fretting is a type of wear and can create a rusty looking finish.  I personally would

The idea behind the spindle locking pin is that it is an extra safety mechanism.  If you lose one or both nuts and washers on the spindle pin it can't slide out, assuming you have one that can actuall

Posted Images

I think the 5/8" bolt is a good alternative but it's main drawback is the shaft of the bolt rotating inside strut/hub housing so you really need to grind out that notch and install the anchor pin as you would with the stock pin.

As for the torque spec. I would check what the specs are for the 5/8" bolt you are using, you can get those bolts/nuts in grade 5 and 8.

Link to post
Share on other sites

Thanks grannyknot.  I'm not really concerned if the bolt can take the torque, I'm more concerned about the fact that the spindle pin has shoulders on both ends which prevent the nuts from being tightened too far where the bolt has threads that would allow you to tighten the nut to the point where the upright would barely be able to turn because there would be so much friction between it and the control arm bushings.  

Link to post
Share on other sites
3 hours ago, fusion said:

Thanks grannyknot.  I'm not really concerned if the bolt can take the torque, I'm more concerned about the fact that the spindle pin has shoulders on both ends which prevent the nuts from being tightened too far where the bolt has threads that would allow you to tighten the nut to the point where the upright would barely be able to turn because there would be so much friction between it and the control arm bushings.  

 

This should be explained in the instructions with the kit, because it should have been addressed when the system was designed.  

Link to post
Share on other sites

The main issue with the 5/8 bolt is that it is a couple thousandth's smaller than the pin, so it is loose in the spindle bore. If you torque the bolt down so that it doesn't move, I think you're OK to use the bolt with no huge issues.

Torquing the bolt shouldn't be a problem with poly bushings in theory, but probably is in practice. The idea with poly is that the sleeve should be tightly held by the bolt, or the nuts on the stock pin. The bushing is intended to rotate around the stationary sleeve. The problem is that the bushings are almost always way wider than the sleeve, so you have to torque the crap out of the bolt in order to hold the pin stationary, and I can tell you from personal experience that this makes the suspension REALLY hard to move. My guess is that most people don't actually tighten this all down correctly, they just tighten it "enough" and if that is the case,  then the bolt can actually pivot in the bore (wearing the bolt), and the bushings can also move around the sleeve. Whichever requires less force is more likely to happen. If you're going with a rod end style control arm, this is really not an issue at all. Torque it down tight enough and you're good.

The solution with poly is to sand the bushings down to reduce the bushing width, so that you don't have to torque the bolt to 100 ft/lbs to compress the bushing enough to lock the sleeve in place. In addition to cutting the length of the bushing down so that there isn't so much compression on the bushing, another thing to do would be to sand away a lot of the surface area on the outer ends so that the resistance to the bushing spinning is reduced. In combination these two things will still control toe change because the bushing extends into the control arm and you wouldn't be removing that part but it will reduce friction A LOT. 

After modding the bushings another thing to look at is adding zerk fittings to the outer ends of the LCA so that the bushings can be greased. Easy to do, works great. What doesn't work is zerks on the inner bushings; the bushing saddles aren't tight enough, so rather than going in between the bushing and sleeve, grease added just squishes out the corners of the bushing saddles.

If you're installing poly bushings, watch this video first and consider the above mods to improve their function. This video talks about a Miata poly bushing with a better design that has these features incorporated, along with cross hatching that allows lubrication to stay in the friction area between bushing and sleeve, which is far better than what Energy Suspension is making for Zs. Probably not enough market to justify doing this for a Z though...


 

Edited by JMortensen
Link to post
Share on other sites

The one thing that hasn't yet been mentioned I'd like to point out is get a bolt long enough so only the shank is against the bushes.  If you buy a bolt that fits it will most likely have threads in one of the bush ends.  I don't think I'd recommend notching for the spindle pin as this will add a failure point and this system doesn't have the fail safe the stock system has.  If you do decide to notch the bolt make sure to paint of put some corrosion inhibitor on it.  

 

cary

Link to post
Share on other sites
  • 1 month later...

I have had a 5/8 bolt in the rear control arm/strut for over 16 years and 250 track days with no issues whatsoever.  I have not found one good reason to use the locking pin and I have several rear control arms from old SCCA EP cars that use either a through bolt or a spindle pin without the locking pin.

 

It's not like I haven't put stress on the control arms...

 

 

NJrear19.jpg

Link to post
Share on other sites
19 hours ago, gnosez said:

I have had a 5/8 bolt in the rear control arm/strut for over 16 years and 250 track days with no issues whatsoever.  I have not found one good reason to use the locking pin and I have several rear control arms from old SCCA EP cars that use either a through bolt or a spindle pin without the locking pin.

 

It's not like I haven't put stress on the control arms...

 

 

NJrear19.jpg

I'm going to quote this post the next time this subject comes up on ClassicZforum, the last time it did I suggested the 5/8" bolt as a replacement for the original pin and got spanked back into my corner.

Hard to argue with 250 track days.

Link to post
Share on other sites

You want the suspension to be able to move without ever binding. Imagine if you will that at as you come off the first portion of the "Bus Stop" at Watkins Glen and one of the rear strut is stuck in the up position. The result is a 3-wheel Citroen DS without the gyro.  While not a Z the car in front of me lost control and nearly flipped over. The bolt and capture nut has never gotten loose.

Link to post
Share on other sites

Yeah I didn’t quite understand the purpose of the spindle lock pin either. I mean, you have bushings in either side. Why can’t the spindle rotate about its axis? Or not rotate. If the ends have locking nuts, what’s gonna happen 🤷🏽‍♂️ 
 

as long as there isn’t play, the control control arm can still rotate bout the spindle, and the thing doesn’t come undone... what can go wrong 

Link to post
Share on other sites
1 hour ago, gnosez said:

You want the suspension to be able to move without ever binding. Imagine if you will that at as you come off the first portion of the "Bus Stop" at Watkins Glen and one of the rear strut is stuck in the up position. The result is a 3-wheel Citroen DS without the gyro.  While not a Z the car in front of me lost control and nearly flipped over. The bolt and capture nut has never gotten loose.


speaking of stress on the control arms, my transvers link mount (I think that’s what it’s called?) had a cracks diagonal along the curved surface that is in contact with the bushing. Anyone else experience this? I welded it up and ground it flush. The car already had a racing history before I got it. 

I also had the control arms sandblasted, stitch welded, primed and coated, but I found a pair of apex ones used for a good deal so now they are paperweights. 

E2BE3ECE-A578-45A1-AA4B-F549ACA9D467.jpeg

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...